Coenzyme Q10, also known as ubiquinone or CoQ10, is a lipophilic, vitamin-like substance present in most eukaryotic cells. Coenzyme Q10 acts as a component of the cellular respiration chain, which generates cellular energy in the form of ATP. It has also been used for the treatment of several diseases, including cardiovascular disease, high blood pressure, muscular dystrophy, and periodontal disease.
Due to its size and structure, coenzyme Q10 is practically insoluble in water, exhibiting an extremely low water solubility of, for example, between 2-3 parts per million (ppm) (i.e., 2-3 mg/L). Because of its low water solubility, previous coenzyme Q10 formulations have shown very low bioavailability when taken as an oral supplement.
Various approaches to improving the bioavailability of coenzyme Q10 have been attempted in the prior art. A common approach involves placing coenzyme Q10 into solution with a water-miscible organic solvent, usually in combination with one or more emulsifiers to form a liquid coenzyme Q10 formulation. For example, U.S. Pat. No. 6,056,971 discloses that the water solubility of coenzyme Q10 is increased when dissolved in a mixture of an edible polyhydric alcohol and a nonionic surfactant. Liquid coenzyme Q10 formulations, however, frequently require the use of soft gelatin capsules, which are relatively expensive to manufacture and exhibit a reduced shelf life as compared to solid tablets. A few approaches use variations on this theme that allow production of solid coenzyme Q10 compositions. For example, U.S. Pat. No. 5,989,583 discloses a composition wherein coenzyme Q10 is dissolved in a digestible fat that is solid at room temperature. This formulation can be spray-chilled to produce solid particles with improved dispersibility in water. Such dried powder coenzyme Q10 formulations in the prior art, however, still exhibit lower levels of water solubility and bioavailability than are desired for effective oral supplementation.
Another method reported to increase the bioavailability of coenzyme Q10 is reducing the particle size to the submicron range. The production of submicron particle sizes through traditional techniques, however, requires significant effort, energy, and expense. For example, U.S. Pat. No. 6,861,447 discloses a method to increase bioavailability by forming a complex of coenzyme Q10 and cyclodextrin, which is subsequently ground into a fine powder using a ball mill. Mechanical milling processes are labor-intensive and expensive to operate, and as such are not ideal for production on a commercial scale.
One approach to increasing the bioavailability of highly lipophilic substances involves the use of colloidal particle compositions. The technology of mixing hydrophobic substances in coating materials, described by Sair et al. in U.S. Pat. No. 4,230,687, has been the basis for creating various forms of stable microdispersions. For example, the process of spray drying an emulsion of lecithin, organic oil and a nonionic poloxamer surfactant was developed for the creation of shelf stable flavorants in the food industry (U.S. Pat. No. 5,362,425). A similar approach has been used to increase the solubility of phytochemicals, described in U.S. Pat. No. 6,086,915 to Zeligs et al. The method of the '915 patent involves co-dissolving the phytochemicals in an appropriate solvent, an emulsifier, and phospholipids, followed by spray-drying the resulting mixture to create solid particles. This process was found to promote enhanced absorption of the phytochemicals when dissolved and emulsified within the small intestine of a human or animal.
Recently, the prior art has begun to apply colloidal technology to improve the solubility of coenzyme Q10 compositions. For example, U.S. Pat. No. 7,026,361 discloses that aqueous dispersibility may be improved by encasing coenzyme Q10 within a protective, water-soluble colloid, which is formed by emulsifying coenzyme Q10 in an aqueous medium in the presence of an organic acid. The composition of the '361 patent can be formulated as either a liquid composition, or as solid particles formed by spray drying. While this technology offers improved solubility relative to more traditional formulations of coenzyme Q10 (e.g., gelatin capsule formulations), it still does not provide the desired level of bioavailability necessary for cost-effective coenzyme Q10 supplementation.
One goal of the present invention is to improve on the methods and compositions in the prior art by producing coenzyme Q10 compositions with improved bioavailability and/or solubility. Another goal of the present invention is to produce a dry powder composition comprising coenzyme Q10 including, for example, dry powder compositions having moisture contents of less than about 2% by weight, or lower. A further goal of the present invention is the provision of coenzyme Q10 products that allow preparation of coenzyme Q10 formulations that exhibit greater stability (e.g., storage stability) than prior coenzyme Q10 formulations. There is significant evidence that ingestion of coenzyme Q10 supplements provides beneficial effects, particularly in the prevention and treatment of various diseases, including cardiovascular disease. Currently available supplements, however, must contain relatively high doses of coenzyme Q10 to compensate for the low bioavailability, resulting in additional expense that is detrimental to consumers. There is therefore a need in the art for an improved coenzyme Q10 composition that exhibits improved bioavailability and/or solubility, is economical for mass production, and suitable for preparation of coenzyme Q10 formulations exhibiting improved storage stability.